From jimr@Maia.usno.navy.mil Tue Jan 6 07:47 EST 1998
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From: Jim Ray (USNO 202-762-1444)
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Subject: IGS/BIPM Project for Time and Frequency Comparisons
To: igsmail@igscb.jpl.nasa.gov, sggmail@cddis.gsfc.nasa.gov
Date: Tue, 06 Jan 1998 7:47:41 EST
Full-Name: Jim Ray (USNO 202-762-1444)
Cc: cthomas@bipm.fr (Claudine Thomas (BIPM)),
tquinn@si.bipm.fr (Terry J. Quinn (BIPM)),
jimr@Maia.usno.navy.mil (Jim Ray (USNO))
X-Mailer: Elm [revision: 109.19]
Status: RO
Author: Jim Ray (USNO) and Claudine Thomas (BIPM)
INTERNATIONAL GPS SERVICE FOR GEODYNAMICS (IGS)
BUREAU INTERNATIONAL DES POIDS ET MESURES (BIPM)
CALL FOR PARTICIPATION
IN AN
IGS/BIPM PILOT PROJECT
TO STUDY ACCURATE TIME AND FREQUENCY COMPARISONS
USING GPS PHASE AND CODE MEASUREMENTS
Background
----------
The International GPS Service for Geodynamics (IGS) and the
Bureau International des Poids et Mesures (BIPM) are
establishing a joint Pilot Project for Time and Frequency
Comparisons using GPS. The goal of this Pilot Project is to
investigate the use of GPS phase and code measurements to
improve worldwide availability of accurate time and frequency.
GPS offers the opportunity for highly accurate time and
frequency transfer among many remote sites. In their analyses
of GPS observations, the IGS Analysis Centers have the
potential for determining clock differences with
uncertainties well below one nanosecond. These results are
comparable to those of the best techniques available. To
exploit this potential, however, important technical issues
remain to be resolved, which this Pilot Project will
investigate.
The Pilot Project is open to all relevant groups, agencies, and
individuals. These activities are not intended to limit in any
way the freedom of participants to engage in independent
research. The objective is to organize and coordinate efforts
among groups to achieve the goals of the Project and to share
resources, data, and experiences. The Pilot Project will be
conducted by a Working Group formed by those responding to this
Call for Participation.
Areas of participation
----------------------
It is expected that the goals of the Pilot Project will require
activities in a variety of areas, including those listed below.
Investigators are invited to participate in one or more areas.
1) Deployment of GPS receivers
In addition to the GPS receivers already installed as part
of the IGS global tracking network, other receivers in
laboratories having accurate time standards are sought.
These should be high-quality geodetic receivers capable of
recording and rapidly transmitting dual-frequency code and
carrier phase observations. The station configuration and
data distribution should conform to IGS standards and
appropriate documentation must be filed with the IGS Central
Bureau; refer to
http://igscb.jpl.nasa.gov/igscb/resource/newstation.txt.
In addition, due consideration should be given to electronic
stability and environmental control. Upgrading of existing
tracking stations for better timing performance is also
encouraged.
2) GPS data analysis
Strategies for analyzing GPS phase and code observations
must be developed, consistent with other IGS products, to
allow the routine, accurate characterization of time
standards at a large number of independent GPS receiver
sites. This work will be done in close cooperation with the
IGS Analysis Coordinator. It is expected that regular
reports will be issued by participating analysis centers,
analogous to those distributed by the IGS for other
activities; refer to
http://igscb.jpl.nasa.gov/mail/IGSREPORT.html.
3) Analysis of instrumental delays
In order to relate clock estimates derived from GPS data
analysis to external timing standards it is necessary to
understand the instrumental electronic delays introduced by
the associated hardware. Studies are sought to characterize
the short-term and long-term sensitivities to
environmental changes and to develop calibration methods.
Differences for the L1 and L2 frequencies must be
considered. Studies of both GPS ground sites as well as the
GPS satellites are sought.
4) Time transfer comparisons
Simultaneous, independent time and frequency comparison data
are needed to compare with the GPS-derived estimates.
Collaborations are sought with groups performing time
transfer experiments using a variety of techniques.
Close cooperation is expected with the Consultative
Committee for Time and Frequency (CCTF) of the Comite
International des Poids et Mesures (CIPM).
Data exchange
-------------
GPS observational data should be distributed using the IGS
hierarchy of data centers and appropriate standards and
formats. Analysis reports should be distributed electronically
as part of the IGS Reports series. In addition, an e-mail
exploder list will be assembled to allow a free exchange of
communications among Working Group members and a World Wide Web
site will be constructed for the Pilot Project.
Organization
------------
The Pilot Project will be conducted by the Working Group formed
by this Call for Participation. The operation of the Working
Group will be self-directed through consensus of the
participants. Subdivision of the Working Group into topical
sub-groups may be considered.
The Working Group will be co-chaired by:
Dr. Jim Ray (USNO), representing IGS
e-mail = jimr@maia.usno.navy.mil
Dr. Claudine Thomas, representing BIPM
e-mail = cthomas@bipm.fr
Schedule
--------
It is anticipated that the schedule of activities will be
reasonably flexible. However, for planning purposes the
following schedule is suggested:
01 Jan. 1998 -- Call for Participation distributed
15 Mar. 1998 -- Responses to Call for Participation due
01 Apr. 1998 -- Establishment of Pilot Project Working Group
01 Jun. 1998 -- Target for publication of first analysis
report
Dec. 1998 -- Interim report to IGS Governing Board
Spring 1999 -- Report to Consultative Committee for Time
and Frequency
Dec. 1999 -- Final report to IGS Governing Board
Response form
-------------
Investigators interested in participating in this Pilot Project
are asked to return the following reponse form by 15 March 1998
to Jim Ray at the e-mail address: jimr@maia.usno.navy.mil, and
to Claudine Thomas at the e-mail address: cthomas@bipm.fr.
----------------------------------------------------------------
Response to CALL FOR PARTICIPATION in an
IGS/BIPM PILOT PROJECT TO STUDY ACCURATE TIME AND FREQUENCY
COMPARISONS USING GPS PHASE AND CODE MEASUREMENTS
Agency or group:
Contact person(s):
E-mail address(es):
Areas of participation:
1) Deployment of GPS receivers: Yes or No
2) GPS data analysis: Yes or No
3) Analysis of instrumental delays: Yes or No
4) Time transfer comparisons: Yes or No
6) Other: (please list)
Limitations on participation: (please list any restrictions)
Comments or suggestions:
Please return to jimr@maia.usno.navy.mil and cthomas@bipm.fr,
preferably by 15 March 1998
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